The research project is a secondary analysis of three existing data sets pertaining to publicly supported methadone maintenance treatment units and their clients. The research examines the relationship of methadone dosage level, program orientation of client control, detoxification policies, service density, program staffing patterns, programs size, and client characteristics to the ability of a program to retain its clients. The data to be examined is drawn from the 1981 National Drug and Alcohol Treatment Unit Survey (NDATUS), the Client Oriented Data Aquisition Process (CODAP), and the 1981 Methadone Treatment Unit Administrators Questionnaire (TUAQ). The TUAQ was administered to a stratified, random sample of methadone maintenance treatment units in the eleven states with the largest number of treatment units nationally. The sample was stratified into "low-dose" programs (45 percent or more clients stabilized at or under 20 mg/day), "mid-dose" programs (45 percent or more clients stabilized between 20 and 60 mg/day), and "high dose" programs (45 percent more clients stabilized above 60 mg/day). The data analysis plan focuses on the effects of the variables listed above, and seeks to define factors which influence retention in either direction, together with the proportions of variation for which they account.